Unicompartmental knee arthroplasty

ABSTRACT

Implants include fixation features which slidingly receive fixation elements. The fixation features may be negative or positive features, such as undercut channels or posts. Examples include unicompartmental tibial trays having a ridge protruding from the bone-facing side, an undercut channel formed within the ridge. Instruments are disclosed for preparing a ridge-receiving feature in bone.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of:

U.S. Provisional Patent Application No. 62/467,083, Attorney's DocketNo. ENG-2 PROV, entitled UNICOMPARTMENTAL KNEE ARTHROPLASTY, which wasfiled on Mar. 3, 2017.

The foregoing is incorporated by reference as though set forth herein inits entirety.

TECHNICAL FIELD

The present disclosure relates to arthroplasty. More specifically, thepresent disclosure is made in the context of unicompartmental kneearthroplasty. Those of skill in the art will appreciate that thedisclosed technology is applicable to other types of arthroplasty.

BACKGROUND

Arthroplasty procedures seek to replace a natural joint that hasdeteriorated in its functionality. Joint resurfacing typically involvesremoval of at least a portion of a natural articular surface of a bonein order to replace the removed tissue with a prosthesis having anarticular surface that replicates at least the removed portion of thenatural articular surface. Joint replacement may involve more extensivebone removal and subsequent replacement with a more substantialprosthesis. In this disclosure, remarks about resurfacing are to beconsidered equally relevant to replacement, and vice versa.

Arthroplasty procedures may involve one or more articular surfaces of ajoint. In the knee, for example, the medial femoral condyle, the lateralfemoral condyle, the medial tibial condyle, the lateral tibial condyle,the trochlear groove, and/or the patella may be resurfaced or replaced.A procedure may be described as unicondylar if one condyle of the jointis treated, such as the medial tibial condyle. Bicondylar procedures maytreat two condyles of a bone, such as the medial and lateral tibialcondyles. A procedure may be described as unicompartmental if onecompartment of the joint is treated, such as the medial compartment ofthe knee. Bicompartmental procedures may treat two compartments, such asthe medial and lateral compartments of the knee. A procedure may bedescribed as a total joint procedure if most or all opposing articularsurfaces of the joint are resurfaced or replaced. A procedure may bedescribed as a hemiarthroplasty procedure if the prosthetic componentarticulates against an opposing natural articular surface, such as theprosthetic medial tibial component articulating against the naturalmedial femoral condyle.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the technology will become more fully apparentfrom the following description and appended claims, taken in conjunctionwith the accompanying drawings. Understanding that these drawings depictonly exemplary embodiments and are, therefore, not to be consideredlimiting of the scope of the technology, the exemplary embodiments willbe described with additional specificity and detail through use of theaccompanying drawings in which:

FIG. 1 is a perspective view of a unicompartmental tibial tray and afixation element;

FIG. 2 is another perspective view of the tibial tray and fixationelement of FIG. 1 from a different direction;

FIG. 3 is a top view of the tibial tray of FIG. 1;

FIG. 4 is a bottom view of the tibial tray and fixation element of FIG.1;

FIG. 5 is a front view of the tibial tray and fixation element of FIG.1;

FIG. 6 is a back view of the tibial tray and fixation element of FIG. 1;

FIG. 7 is a left view of the tibial tray and fixation element of FIG. 1;

FIG. 8 is a right view of the tibial tray and fixation element of FIG.1;

FIG. 9 is an auxiliary view of the tibial tray and fixation element ofFIG. 1 perpendicular to a plane of symmetry along the length of thefixation element, the tibial tray shown in cross section taken throughthe plane of symmetry of the fixation element;

FIG. 10 is another auxiliary view of the tibial tray and fixationelement of FIG. 1 taken along line 10-10 of FIG. 9 parallel to the planeof symmetry of the fixation element;

FIG. 11 is a cross sectional view of the tibial tray and fixationelement of FIG. 1 taken along line 11-11 of FIG. 9;

FIG. 12 is a cross sectional view of the tibial tray and fixationelement of FIG. 1 taken along line 12-12 of FIG. 9;

FIG. 13 is a cross sectional view of the tibial tray and fixationelement of FIG. 1 taken along line 13-13 of FIG. 9;

FIG. 14 is a cross sectional view of the tibial tray and fixationelement of FIG. 1 taken along line 14-14 of FIG. 9;

FIG. 15 is a cross sectional view of the tibial tray and fixationelement of FIG. 1 taken along line 15-15 of FIG. 9;

FIG. 16 is a cross sectional view of the tibial tray and fixationelement of FIG. 1 taken along line 16-16 of FIG. 9;

FIG. 17 is a cross sectional view of the tibial tray and fixationelement of FIG. 1 taken along line 17-17 of FIG. 9;

FIG. 18 is a bottom view of the tibial tray of FIG. 1;

FIG. 19 is a perspective view of the tibial tray of FIG. 1;

FIG. 20 is left view of the tibial tray of FIG. 1;

FIG. 21 is a right view of the tibial tray of FIG. 1;

FIG. 22 is another auxiliary view of the tibial tray of FIG. 1 takenalong line 10-10 of FIG. 9 parallel to the plane of symmetry of thefixation element;

FIG. 23 is a cross sectional view of the tibial tray of FIG. 1 takenalong line 11-11 of FIG. 9;

FIG. 24 is a cross sectional view of the tibial tray of FIG. 1 takenalong line 12-12 of FIG. 9;

FIG. 25 is a cross sectional view of the tibial tray of FIG. 1 takenalong line 17-17 of FIG. 9;

FIG. 26 is a perspective view of the fixation element of FIG. 1;

FIG. 27 is a front view of the fixation element of FIG. 1;

FIG. 28 is a bottom view of the fixation element of FIG. 1;

FIG. 29 is a right view of the fixation element of FIG. 1;

FIG. 30 is a cross sectional view of the fixation element of FIG. 1taken along line 11-11 of FIG. 9;

FIG. 31 is a cross sectional view of the fixation element of FIG. 1taken along line 12-12 of FIG. 9;

FIG. 32 is a cross sectional view of the fixation element of FIG. 1taken along line 13-13 of FIG. 9;

FIG. 33 is a cross sectional view of the fixation element of FIG. 1taken along line 14-14 of FIG. 9;

FIG. 34 is a cross sectional view of the fixation element of FIG. 1taken along line 15-15 of FIG. 9;

FIG. 35 is a cross sectional view of the fixation element of FIG. 1taken along line 16-16 of FIG. 9;

FIG. 36 is a cross sectional view of the fixation element of FIG. 1taken along line 17-17 of FIG. 9;

FIG. 37 is a perspective view of a unicondylar drill guide and a drill;

FIG. 38 is another perspective view of the drill guide and drill of FIG.37;

FIG. 39 is a top view of the drill guide and drill of FIG. 37;

FIG. 40 is a bottom view of the drill guide and drill of FIG. 37;

FIG. 41 is a front view of the drill guide and drill of FIG. 37;

FIG. 42 is a back view of the drill guide and drill of FIG. 37;

FIG. 43 is a left view of the drill guide and drill of FIG. 37;

FIG. 44 is a right view of the drill guide and drill of FIG. 37;

FIG. 45 is a perspective view of the drill guide of FIG. 37;

FIG. 46 is a perspective view of the drill of FIG. 37;

FIG. 47 is a top view of the drill of FIG. 37;

FIG. 48. is a left view of various embodiments of trays; and

FIG. 49. is a right view of various embodiments of trays.

DETAILED DESCRIPTION

Exemplary embodiments of the technology will be best understood byreference to the drawings, wherein like parts are designated by likenumerals throughout. It will be readily understood that the componentsof the technology, as generally described and illustrated in the figuresherein, could be arranged and designed in a wide variety of differentconfigurations. Thus, the following more detailed description of theembodiments of the apparatus, system, and method is not intended tolimit the scope of the invention, as claimed, but is merelyrepresentative of exemplary embodiments of the technology.

The phrases “connected to,” “coupled to” and “in communication with”refer to any form of interaction between two or more entities, includingmechanical, electrical, magnetic, electromagnetic, fluid, and thermalinteraction. Two components may be functionally coupled to each othereven though they are not in direct contact with each other. The term“abutting” refers to items that are in direct physical contact with eachother, although the items may not necessarily be attached together. Thephrase “fluid communication” refers to two features that are connectedsuch that a fluid within one feature is able to pass into the otherfeature.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. While the various aspects of theembodiments are presented in drawings, the drawings are not necessarilydrawn to scale unless specifically indicated.

Standard medical planes of reference and descriptive terminology areemployed in this specification. While these terms are commonly used torefer to the human body, certain terms are applicable to physicalobjects in general.

A standard system of three mutually perpendicular reference planes isemployed. A sagittal plane divides a body into right and left portions.A coronal plane divides a body into anterior and posterior portions. Atransverse plane divides a body into superior and inferior portions. Amid-sagittal, mid-coronal, or mid-transverse plane divides a body intoequal portions, which may be bilaterally symmetric. The intersection ofthe sagittal and coronal planes defines a superior-inferior orcephalad-caudal axis. The intersection of the sagittal and transverseplanes defines an anterior-posterior axis. The intersection of thecoronal and transverse planes defines a medial-lateral axis. Thesuperior-inferior or cephalad-caudal axis, the anterior-posterior axis,and the medial-lateral axis are mutually perpendicular.

Anterior means toward the front of a body. Posterior means toward theback of a body. Superior or cephalad means toward the head. Inferior orcaudal means toward the feet or tail. Medial means toward the midline ofa body, particularly toward a plane of bilateral symmetry of the body.Lateral means away from the midline of a body or away from a plane ofbilateral symmetry of the body. Axial means toward a central axis of abody. Abaxial means away from a central axis of a body. Ipsilateralmeans on the same side of the body. Contralateral means on the oppositeside of the body. Proximal means toward the trunk of the body. Proximalmay also mean toward a user or operator. Distal means away from thetrunk. Distal may also mean away from a user or operator. Dorsal meanstoward the top of the foot. Plantar means toward the sole of the foot.

Standard terminology related to knee arthroplasty is employed in thisspecification with the ordinary and customary meanings. Varus meansdeviation of the distal part of the leg below the knee inward, resultingin a bowlegged appearance. Valgus means deviation of the distal part ofthe leg below the knee outward, resulting in a knock-kneed appearance.

Referring to FIGS. 1-36, a knee tibial prosthesis 10 includes a tibialcomponent 50 and at least one fixation element 20. The tibial component50 may be referred to as a tibial tray 50. The illustrated tibialcomponent 50 is a unicompartmental tibial component. The tibialprosthesis 10 of FIG. 1 includes one fixation element 20, which may bereferred to as an anchor 20. Multiple anchors may be present. The anchor20 may be inserted from an anterior edge 54 of the tibial tray 50 andmay be oriented roughly anterior-posterior, as shown. The anchor 20 maybe parallel or angled relative to another anchor (if present) and/or thetray 50. The anchor may also be tilted with respect to the tray 50, forexample, tilted medially or laterally. The anchor 20 is inserted into achannel 52 in the tibial tray 50 (FIG. 18). Multiple channels may bepresent. The channel may be dovetailed as shown; other undercut channelgeometries are contemplated, such as T-slots. The channel 52 is shownextending between anterior and posterior edges 54, 66 of the tray 50. Insome embodiments, the channel may only open at one of the anterior andposterior edges 54, 66, and may terminate in the main body of the tray50. In other examples, the channel 52 may be oriented exactlyanterior-posterior, exactly medial-lateral, generally medial-lateral, orin another orientation. A channel 52 may open through any perimeter edgeof a bone-contacting side 56 of the tray 50.

The anchors in the present disclosure may share some or all of thefeatures of the anchors disclosed in U.S. patent application Ser. No.12/640,892 to Bae, et al. or U.S. patent application Ser. No. 13/328,592to Bae, et al., which are incorporated by reference herein in theirentirety.

Referring mainly to FIGS. 26-36, each fixation element or anchor 20comprises a blade 22 and a rail 24. The blade and rail extend between aleading end 70 and a trailing end 68 of the anchor. The leading end 70may also be referred to as a distal end 70; the trailing end 68 may alsobe referred to as a proximal end 68. Supports 26 connect the blade 22 tothe rail 24. FIG. 26 illustrates an anchor 20 with three supports 26,although other examples may include any number of supports. The supports26 define apertures 27 through the anchor 20. In use, the blade 22 andat least a portion of the supports 26 may be inserted into bone which isadjacent to the bone-contacting side 56 of the tray 50. The blade 22 maybe pointed, sharpened, and/or serrated, for ease of insertion into bone.The supports 26 may also be sharpened and/or obliquely profiled for easeof insertion into bone. The blade edges may be beveled. The blade 22 maybe pierced by one or more apertures 36. Longitudinal edges 28 of therail may be sized and shaped for complementary engagement with thedovetail channels 52 of the tray 50. In other examples, the rail may beof a complementary size and shape to engage another undercut channelgeometry.

There may be a small tab 30 projecting from the rail 24. FIGS. 32 and 36illustrate bilateral tabs. The tab may be said to protrude laterally ortransversely from the rail 24. The tab deforms as the anchor is driveninto the tibial tray 50, creating an interference fit. This materialdeformation serves to take up any relative motion between the anchor andthe tibial tray as well as to lock the anchor 20 into the tray 50. Thedeformation may be characterized as plastic deformation, which may be atleast partially irreversible. The deformation may cause galling, spotwelding, and/or seizing to occur between the tab and the channel 52. Anyof these adhesive phenomena may lock the anchor to the tray. There maybe a physical stop 32 on the anchor to prevent over-insertion. FIGS. 28and 29 illustrate bilateral stops. A distal tip 34 of the anchor railmay be tapered for ease of insertion into, and movement along, thechannels 52. In FIGS. 26-36, physical stops 32 are located on each sideof the rail 24 and extend distally from the proximal end 68. Tabs 30 arelocated on each side of the rail 24 near the proximal end 68, spacedapart distally from the physical stops 32. Another example may include atab 30 on only one side of the rail. The illustrated example includes asecond pair of bilateral interference tabs 31 located on each side ofthe rail 24 and spaced apart distally from the tabs 30. The tabs 31 areshown adjacent to a middle support 26, although they can be locatedanywhere along the rail 24 between the tabs 30 and the distal end 70.This arrangement may provide even greater fixation along the length ofthe anchor in the channel 52. Also, in other embodiments the length,height, or other dimensions of the anchor may vary.

To achieve optimal compression between the bone and the tibial tray, theanchor blade 22 may be angled divergent from the rail 24. At theleading, distal end 70 of the anchor 20, the blade 22 and the rail 24may be farther apart than they are at the trailing, proximal end 68 ofthe anchor. The divergence angle 72 may be less than about 90 degrees.In some examples, the divergence angle may be less than about 15degrees, less than about 5 degrees, or less than about 2 degrees. In theembodiment shown, the divergence angle between the blade 22 and the rail24 is 1 degree. Divergence angles of less than 1 degree are alsocontemplated.

When the anchor rail 24 is inserted into the channel 52 of the tibialtray 50, the anchor blade 22 may diverge from an inferior orbone-contacting side 56 of the tray 50 at the same angle 72.Alternatively, the blade 22 may diverge from the inferior orbone-contacting side of the tray 50 at another angle, which may begreater than or less than the blade-to-rail divergence angle 72.Furthermore, the blade-to-tray divergence angle may open in the same oropposite direction as the blade-to-rail divergence angle 72.

The angle 72 between the blade 22 and the rail 24, and/or the anglebetween the blade and the bone-contacting side 56 may correlate to themechanical properties of the bone into which the anchor 20 will beinserted, the desired amount of compression between the bone and thebone-contacting side, the compliance of the bone-contacting side, and/orother factors. For example, larger divergence angles may be appropriatefor conditions such as: softer bone, greater compression, and/or acompliant bone-contacting side; smaller divergence angles may beappropriate for conditions such as harder or stiffer bone, lesscompression, and/or an unyielding bone-contacting side. The divergenceangle may also correlate to the length of the anchor 20, with greaterdivergence angles possible with shorter anchors and smaller divergenceangles suitable for longer anchors.

Referring mainly to FIGS. 1-8, 10 and 19-25, the tibial tray 50 includesa bone-contacting, or inferior side 56 across which the channel 52extends. A ridge 76 extends across the bone-contacting side 56 toprovide material within which to form the channel 52. In this example,the entire channel 52 is outside the main body of the tibial tray 50, asseen best in FIGS. 22-24. In other words, the most proximal surface 53within the channel is flush with or distal to the inferior side 56.Surface 53 may be referred to as the bottom surface of the channel. Thechannel 52 is thus defined between first and second walls 77, 78. At oneend of each channel 52, shoulders 59 are formed in the edges of thechannels 52. The shoulders 59 are illustrated as being formed ininterior edges of the channel near the anterior edge 54 of the tibialtray 50. As seen in FIG. 4, when the anchor rail 24 is inserted throughthe channel, the shoulders 59 deform the tabs 30 and engage with thestops 32 to provide the interference fit between the anchors 20 and thetray 50, and to properly position the anchors at the correct depthrelative to the tray. A peg 58 or post provides further fixation of thetray 50 in the tibia. The illustrated example includes a second peg 57or post; any number of pegs may be present. The pegs 57, 58 protrudefrom the bone-contacting side 56 and form an angle 74 with thebone-contacting side. The angle 74 may be up to 90 degrees; a 75 degreeangle 74 is illustrated for both pegs 57, 58. The pegs extend in aninferior-posterior direction from the bone-contacting side 56, althoughthe pegs may extend in other directions as a matter of design choice.

The tibial tray 50 further includes a joint-facing, or superior side 60to which an articular insert (not shown) may be mounted, or thejoint-facing side 60 may include a prosthetic articular surfaceintegrally formed with the tibial tray 50. A raised rim 62 encompassesthe superior side 60, and overhangs 64 are formed on a portion of therim 62 for engagement with an articular insert and/or instruments. Therim 62 and overhangs 64 together define a recess 63 that may receive anarticular insert, and may also engage an anchor guide instrument (notshown). The articular insert or instrument may engage under theoverhangs 64 to be held rigidly in the tray 50, for example by a snapfit. Tibial tray 50 may be described as a unicondylar tibial componentbecause it is adapted to extend across a single resected tibial condyleto replace the medial or lateral condyle.

In other embodiments, the features of the tibial tray 50 may vary. Forexample, the peg 58 or other fixation features may vary; the size andthickness of the tray 50 may vary, the outer peripheral size and shapemay vary. Different connection features for engagement with an articularinsert may be incorporated. Other features of tibial trays known in theart may be included as desired. The articular insert may carry theprosthetic articular surface.

Referring to FIGS. 48-49, examples of other embodiments of the tray areshown with tibial tray 50. Tibial tray 94 includes a continuous channel88 that is recessed entirely within the body of the tibial tray. Tibialtray 94 may share some or all of the features of the tibial tray 310disclosed in U.S. patent application Ser. No. 13/328,592 to Bae, et al.Tibial tray 96 includes a channel 90 that includes a series of discretechannel elements within discrete ridges, or between discrete wallsections. A linear array of ridges or walls is shown. Channel 90 extendsalong the bone-contacting surface outside the main body of the tibialtray like channel 52. Tibial tray 98 is an example in which the negativefeature of the channel is replaced by a positive connection feature 92that includes a series of discrete connection elements, which may bereferred to as posts or buttons. Not shown, the fixation elementcorresponding to tray 98 carries a negative feature, a channel, that iscomplementary to the positive connection feature 92. As in the otherembodiments disclosed herein, the posts and channel may be complementaryundercut shapes.

Referring to FIGS. 37-47, a guide and drill assembly 100 includes atibial drill guide 110 and a reamer 150. The tibial drill guide 110corresponds to the tibial tray 50. The reamer 150 is sized to correspondto the ridge 76.

Referring mainly to FIGS. 37-45, the tibial drill guide 110 includes ashaft 112 and a body 114. The shaft 112 extends between a proximal end116 and a distal end 118 and includes a central longitudinal axis 121and a central longitudinal hole 120 that extends entirely through thetibial drill guide 110. The body 114 corresponds to the main body of thetibial tray 50, and may be said to mimic or replicate the main body ofthe tibial tray 50, the perimeter of the main body, or thebone-contacting side 56. The body 114 is coupled to the distal end 118of the shaft 112 so that the axis 121 and hole 120 are located tocorrespond to the height and width of the ridge 76 as viewed in FIG. 10.The body 114 includes holes 122, 124 which correspond to the pegs 58,57, respectively, of the tibial tray 50. The holes 122, 124 may bedefined by optional bosses 126, 128, respectively, to extend the lengthof the holes 122, 124 and/or to provide depth stops for greater accuracyin drilling holes for the pegs 58, 57. The holes 122, 124 receive adrill (not shown) sized according to the outer diameter of the pegs 58,57. The body 114 also includes holes 130, 132 which receive bone pins(not shown) or other fasteners to secure the tibial drill guide 110 tothe tibia in use.

Referring mainly to FIGS. 46-47, the tibial reamer 150 includes a shaft152 that extends between a proximal end 154 and a distal end 156 andincludes a central longitudinal axis 158 about which the reamer 150rotates in use. The proximal end 154 includes a torque drive feature160, such as a hex key or three equilateral flats. The distal end 156includes a cutting section 162 that may be side-cutting, end-cutting, orboth. Between the torque drive feature 160 and the cutting section 162,an optional flange 164 encircles the shaft 152 to serve as a depth stopagainst the proximal end 116 of the shaft 112 of the tibial drill guide110. The distance between the cutting section 162 and the flange 164 maybe related to the overall length of the tibial drill guide along theaxis 121 so that the cutting section 162 is prevented from extendingdistally across the body 114 past the end of the ridge 76. The outerdiameter of the cutting section 162, as well as the outer diameter ofthe shaft 152 distal to the flange 164, are sized to fit in the hole 120of the shaft 112 of the tibial drill guide 110. The outer diameter ofthe flange 164 is larger than the hole 120.

When the cutting section 162 is inserted into the hole 120 and advancedto be adjacent to the body 114, a portion of the cutting section 162 isexposed on the bone-contacting side of the body 114 and protrudesoutwardly from the bone-contacting side of the body 114. When thebone-contacting side of the body 114 is placed against a resected bonesurface, the reamer 150 is actuated (rotated about axis 158), and thereamer 150 is moved distally and proximally within the hole 120, thecutting section 162 cuts a groove across the resected bone surface thatis deep enough, wide enough, and long enough to receive the ridge 76 ofthe tibial tray 50. The groove may receive the ridge 76 with clearance,with a line-to-line fit, or with interference (a press fit).

In a method of use, a tibia proximal end is prepared to receive thetibial tray 50. A transverse resection may be made to remove the medialor lateral proximal tibial articular cartilage. Recesses for a tray peg58 and/or 57 may be reamed, drilled, broached, cut or otherwiseprepared. The tibial tray 50 is fit onto the prepared tibia, and may beimplanted with or without cement. An anchor 20 is inserted into thechannel on the tray. The blade may cut into the bone as the anchor isinserted. As the anchor is inserted, the angled configuration of theanchor causes compression of the tray toward the tibia; i.e., the trayis pulled toward the tibia. The tabs, stops, and shoulders on the trayand the anchor cooperate to seat the anchor at the proper depth relativeto the tray, and prevent unintentional withdrawal of the anchor. Anarticular insert (not shown) may be coupled to the superior surface ofthe tray 50, and may include an articular surface.

Referring to FIG. 27, it can be appreciated that the act of insertinganchor 20 into channel 52 and adjacent bone may be described as asequence of events. The leading end 70 is configured so that the rail 24and the blade 22 are the leading features, and are thus the firstfeatures to engage the channel or bone. The leading point of the blade22 penetrates the bone. The leading support 26 is the next feature toengage, as it enters the channel and the bone. The support may be saidto protrude through the bone-contacting surface, since the supportextends through the open side of the channel. All leading edges of thesupport and blade are sharpened and obliquely oriented to reduce theeffort necessary to cut through the bone.

Any methods disclosed herein includes one or more steps or actions forperforming the described method. The method steps and/or actions may beinterchanged with one another. In other words, unless a specific orderof steps or actions is required for proper operation of the embodiment,the order and/or use of specific steps and/or actions may be modified.

Reference throughout this specification to “an embodiment” or “theembodiment” means that a particular feature, structure or characteristicdescribed in connection with that embodiment is included in at least oneembodiment. Thus, the quoted phrases, or variations thereof, as recitedthroughout this specification are not necessarily all referring to thesame embodiment.

Similarly, it should be appreciated that in the above description ofembodiments, various features are sometimes grouped together in a singleembodiment, Figure, or description thereof for the purpose ofstreamlining the disclosure. This method of disclosure, however, is notto be interpreted as reflecting an intention that any claim require morefeatures than those expressly recited in that claim. Rather, as thefollowing claims reflect, inventive aspects lie in a combination offewer than all features of any single foregoing disclosed embodiment.Thus, the claims following this Detailed Description are herebyexpressly incorporated into this Detailed Description, with each claimstanding on its own as a separate embodiment. This disclosure includesall permutations of the independent claims with their dependent claims.

Recitation in the claims of the term “first” with respect to a featureor element does not necessarily imply the existence of a second oradditional such feature or element. Elements recited inmeans-plus-function format are intended to be construed in accordancewith 35 U.S.C. § 112 Para. 6. It will be apparent to those having skillin the art that changes may be made to the details of theabove-described embodiments without departing from the underlyingprinciples of the technology.

While specific embodiments and applications of the present technologyhave been illustrated and described, it is to be understood that thetechnology is not limited to the precise configuration and componentsdisclosed herein. Various modifications, changes, and variations whichwill be apparent to those skilled in the art may be made in thearrangement, operation, and details of the methods and systems of thepresent technology disclosed herein without departing from the spiritand scope of the technology.

1. A system comprising: a tibial tray comprising a body having ajoint-facing side and an opposite bone-facing side, wherein a ridgeprotrudes from and extends across the bone-facing side, wherein anundercut channel extends across the bone-facing side within the ridge; atibial drill guide comprising a body and a shaft, wherein the tibialdrill guide body corresponds to the tibial tray body, wherein the shaftis coupled to the tibial drill guide body, wherein a hole extendsthrough the tibial drill guide along the shaft; and a reamer comprisinga distal cutting section, wherein the distal cutting section is receivedin the hole; wherein, when the distal cutting section is inserted intothe hole and advanced to be adjacent to the tibial drill guide body, afirst portion of the distal cutting section is exposed on a bone-facingside of the tibial drill guide body and protrudes outwardly from thebone-facing side of the tibial drill guide body.
 2. The system of claim1, wherein the ridge is a first ridge of a series of discrete ridgesthat protrude from and extend across the bone-facing side, wherein theundercut channel is a first undercut channel of a series of discreteundercut channel elements within the discrete ridges.
 3. The system ofclaim 1, wherein the entire undercut channel is outside the tibial traybody.
 4. The system of claim 3, wherein the tibial tray joint-facingside faces proximally, wherein the tibial tray bone-facing side facesdistally, wherein the entire undercut channel is flush with or distal tothe tibial tray bone-facing side.
 5. The system of claim 1, wherein thefirst portion of the distal cutting section protrudes outwardly from thebone-facing side of the tibial drill guide body to correspond to theridge.
 6. A system comprising: a tibial tray comprising a body having ajoint-facing side and an opposite bone-facing side, wherein a first wallprotrudes from and extends across the bone-facing side, wherein a secondwall protrudes from and extends across the bone-facing side beside thefirst wall, wherein an undercut channel extends across the bone-facingside between the first and second walls; a tibial drill guide comprisinga body and a shaft, wherein the tibial drill guide body comprises abone-facing side that replicates the tibial tray bone-facing side,wherein the shaft is coupled to the tibial drill guide body, wherein ahole extends through the tibial drill guide along the shaft; and areamer comprising a distal cutting section, wherein the distal cuttingsection is received in the hole; wherein, when the distal cuttingsection is inserted into a proximal end of the hole and advanceddistally next to the tibial drill guide body, a first portion of thedistal cutting section is exposed on the tibial drill guide bodybone-facing side and protrudes outwardly from the tibial drill guidebody bone-facing side.
 7. The system of claim 6, wherein the first andsecond walls are periodically interrupted by gaps to form a series ofdiscrete wall sections, wherein the undercut channel is a first undercutchannel of a series of discrete undercut channel elements between thediscrete wall sections.
 8. The system of claim 6, wherein the entireundercut channel is outside the tibial tray body.
 9. The system of claim8, wherein the tibial tray joint-facing side faces proximally, whereinthe tibial tray bone-facing side faces distally, wherein the entireundercut channel is flush with or distal to the tibial tray bone-facingside.
 10. The system of claim 6, wherein the first portion of the distalcutting section protrudes outwardly from the tibial drill guide bodybone-facing side to correspond to the first and second walls.
 11. Asystem comprising: an implant comprising a body having a joint-facingside and an opposite bone-facing side, wherein a first wall protrudesfrom and extends across the bone-facing side, wherein a second wallprotrudes from and extends across the bone-facing side beside the firstwall, wherein an undercut channel extends across the bone-facing sidebetween the first and second walls; a drill guide comprising a body anda shaft, wherein the drill guide body comprises a bone-facing side thatmimics the implant bone-facing side, wherein the shaft extends between afirst end and an opposite second end, wherein the second end of theshaft is coupled to the drill guide body, wherein a hole extends throughthe drill guide along the shaft; and a reamer comprising a cuttingsection, wherein the cutting section is received in the hole; wherein,when the cutting section is inserted into the first end of the hole andadvanced next to the drill guide body, a first portion of the cuttingsection is exposed on the drill guide body bone-facing side andprotrudes outwardly from the drill guide body bone-facing side.
 12. Thesystem of claim 11, wherein the first and second walls are periodicallyinterrupted by gaps to form a series of discrete wall sections, whereinthe undercut channel is a first undercut channel of a series of discreteundercut channel elements between the discrete wall sections.
 13. Thesystem of claim 11, wherein the entire undercut channel is outside theimplant body.
 14. The system of claim 13, wherein the implantjoint-facing side faces proximally, wherein the implant bone-facing sidefaces distally, wherein the entire undercut channel is flush with ordistal to the implant bone-facing side.
 15. The system of claim 11,wherein the first portion of the cutting section protrudes outwardlyfrom the drill guide body bone-facing side to correspond to the firstand second walls.